Improved iron-roof purlin



@anni 4 GEORGE HALSTEAD, OF BUFFALO, NEW YORK.

Letters Patent No. 91,740, dated June 22, 1869.

IMPROVED IRONROOF PURLIN.

The Schedule referred 'co in these Letters Patent and making part of the same.

To all whom it mwy concern Be it known that I, GEORGE HALSTEAD, of thc city of Buffalo, county of Erie, and State of New York, have invented certain new and useful Improvements in Iron-Roof Purlins; 'and I do hereby declare that the following is a full, clear,` and exact description thereof, reference being had to the accompanying drawings, making a part of this specification;

The nature of my invention consists- First, informing the upper flange of the purlin upon one side of the web, and at an angle thereto cor 'responding tothe pitch of the roof in which it is to be employed, so that the purlin may be applied to the rafters with the plane of vits web vertical and coincident with Athe vdirection of pressure, thus securing a maximum of streugth'with a given area of section, a

result not accomplished with the common form of purthe web of the rafter, whereby-the purlin is secured inits place both vertically and laterally.

VIn the accompanying drawings- Figure I is Aan'isometrical view of two purlins'and.

a rafter, the purlins being slightly removed fromth'e rafter, to show more clearly the configuration of their ends.

Figure II `is an isometrical view, showing the purlins in position upon the. rafter.

Figure Ill shows in section and elevation the same parts as in Fig. I. Like letters refer to like parts in each-of the figures. A represents the rafter, of :l2-form; and B B, the purlins,,the upper flange C, of which projects from one side of the web only, and obliquely thereto, its anglebeing governed by the pitch of the rafter with which it is to connect.

-The lower edge of the web is strengthened by a bead, d.

The ends, of the purlins are notched in the web, as shown at e, `to the form of the flange of rafter, so that when they are applied thereto, as in Fig. II, their npper tia-nge will overlap on the upper side of the flange of ther-after, and `the notched end of the'web passes under said flange, and up to the web of the rafter.

A tenon, f, is formed at the end of the purlin-web,

and a lozenge-shapedmortise, g, is cut through the web of the rafter, which receives said tenon when the parts are brought together, as in Fig. II.`

The mortise is made wide enough to receive the tenon of twopurlin's applied upon opposite sides of the rafter.

By this simple means of connection, .the purlin is supported against vertical strains `by both overlapping fiange and tenon, and is held against lateral movement on the rafter by the tenon. n"

No bolts or rivets are required in the connection, and no metal is taken from the flanges to weaken the rafter, and that which is taken'i'rom the web hy the mortises is so near the nentralaxis as 'notte materially effect its strength.

Ample allowance for expansion and contraction may be made by leaving proper clearance between the end of the purlin and the rafter.

By the oblique position ofthe purlin'flange, its web is made vertical when in position on the rafter, and as the load always acts in a vertical direction, the web is ymade to yield its maximum of strength.

v In the common forms of purlins, the flangeheilig at right anglestothe web, causes the latter to assume lan inclined position when placed upon the rafter, so that the'direction of the pressure passes through it QbliqueIy, thus greatly weakening its power to resist ilexure.

Having thus described'my invention,

Vha't I claim, and desire to secure by-Letters Patent, is-

1. An iron purlin for roofs, having its flange oblique to the web, and arranged, in relation to the rafter, as and for the purpose set forth.

2. The iron purlin B, constructed as described, with an overlapping iange, C, tenon f, and fitted 'to the y rafter, substantially as described.

GEORGE HALSTEAD.

Witnesses:

W. H. FoRBnsH, V. H. BECKER. 

